For what it's worth, I had a thread going in which I did some controlled tests on Rodinal 1+100 stand development (using FP4+) to get an idea of what actually happens. These were tests on roll film in a tank. I had planned on additional tests using sheet film developed horizontally, but the thread went nutso real quick, as usual (rational discussions on stand development and/or Rodinal are impossible) so I never got to the sheet film tests.
The reference developer in these tests was XTOL.
I plotted some sensitometric curves and posted them in that thread, but since sensitometry is sometimes frowned upon

, here are the high level observations without detail:
1) 30 minutes produced a curve almost identical to normal development in XTOL. This means essentially ISO speed or slightly higher.
2) 60 minutes produced an expected push result. Using a fixed density speed determination, one would say there was a "real" speed increase of 1/2 stop to 1 stop, however contrast was substantially higher than normal. The benefit a p-Aminophenol developer such as Rodinal provides under these circumstances is low fog (virtually the same as with normal development).
3) Uniformity was terrible, however depending on subject matter and exposure relationships in the negative, you may or may not find it to be a deal breaker. Given the popularity of this process with roll film, evidently some people either don't notice the poor uniformity, streaking etc., or don't care. Up to the individual user.
Some additional info on XTOL: Dilution will tend to affect image structure more than speed/contrast. Depending on the film (always an important variable) and agitation technique, relative to 1+0, a 1+3 dilution can produce a
very small increase in emulsion speed for a given contrast (or very slightly lower contrast for a given emulsion speed). In any case, When developed normally, XTOL can generally be expected to give a little more speed than Rodinal. If we use D-76/ID-11 as a benchmark producing ISO speed, normal development in Rodinal will tend to produce slightly less speed than D-76, while XTOL will tend to produce slightly more speed than D-76.